This invention relates to a nut cracking machine and in particular to a machine for continuous cracking of hard shell nuts that may vary in size.
Prior art nut cracking machines have used various techniques to crack the shell of different nuts. For certain hard to shell nuts such as the macadamia nut, spaced rollers have been conventionally used to crack the thick protective shell by pressure of the rollers. The rollers are spaced a predetermined distance apart and the nuts are fed between the rollers for cracking. In order that the appropriate pressure be applied to the nut shells to properly free the meat from the shell without crushing the kernel, the nuts must be graded according to size. Similarly, in the nut shelling machine described in the patent of these inventors, entitled "Nut Shelling Machine," U.S. Pat. No. 4,793,248, issued Dec. 27, 1988, opposed blades engage and split the thick shell of the macadamia. The nuts must be pre-sized such that the blades penetrate the shell to the proper depth to effect splitting without damage to the nut.
Sorting nuts according to size is a difficult task since nuts are rarely of uniform configuration. Even nuts such as macadamia nuts, which are generally spherical in configuration, vary both in size and shape. Individual nuts may have flat sides or be oblong in shape. Conventional methods for grading nuts, using grates with progressively larger slots through which the nuts can drop, or progressively, sized screens arranged in a series may result in sorting errors because of the orientation of nonuniform nuts as they pass over the grading openings.
Nuts that are too small for a particular setting of a shelling machine may pass unshelled or be incompletely shelled. Nuts that are too large for a particular machine setting may be crushed, fragmenting the kernel. Whole nuts naturally command a premium price, and while fragments can be salvaged, a resulting loss in value occurs. Unshelled or partially shelled nuts must be reprocessed, and because of their shape or partially shelled condition, usually become fragmented on reprocessing.
A nut cracking machine that can effectively shell nuts that vary in size without presorting of the nuts according to size is therefore desirable. Additionally, a shelling machine that can effectively reprocess nuts that are partially shelled with minimum damage to the remaining kernel would be of value to existing operations.
It is an object of the nut cracking machine of this invention that pressure cracking of nuts of various size is accomplished in a continuous process. It is a further object of this invention that the nut cracking machine can reprocess nuts and effectively orient partially shelled nuts for maximum recovery of whole kernels. These and other objects are satisfied by the nut cracking machine described herein.